Divertor and Impurity Modeling of Impurity Flows and Screening in Alcator C-Mod PDF Download
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Author: Taekyun Chung Publisher: ISBN: Category : Languages : en Pages : 26
Book Description
We report on impurity transport modeling using the DIVIMP code which is able to qualitatively reproduce the poloidal variation of non-recycling impurity penetration factor (PFNR) found in C-Mod experiments: a lower PFNR is computed at the inboard (3.6 %) and divertor target locations (0.7 %) than at the outboard (11 %). By artificially increasing the modeled inner SOL plasma flow to correspond to measured values, a better quantitative agreement between modeled and measured PFs is achieved. We have also roughly reproduced the observed penetration factor for recycling impurities both in time dependence and magnitude. The model has shown that under attached conditions, the majority of recycling impurity ions flow into the confined plasma through the outboard side separatrix. For detached conditions the impurity influx across the separatrix is more concentrated near the divertor.
Author: Taekyun Chung Publisher: ISBN: Category : Languages : en Pages : 26
Book Description
We report on impurity transport modeling using the DIVIMP code which is able to qualitatively reproduce the poloidal variation of non-recycling impurity penetration factor (PFNR) found in C-Mod experiments: a lower PFNR is computed at the inboard (3.6 %) and divertor target locations (0.7 %) than at the outboard (11 %). By artificially increasing the modeled inner SOL plasma flow to correspond to measured values, a better quantitative agreement between modeled and measured PFs is achieved. We have also roughly reproduced the observed penetration factor for recycling impurities both in time dependence and magnitude. The model has shown that under attached conditions, the majority of recycling impurity ions flow into the confined plasma through the outboard side separatrix. For detached conditions the impurity influx across the separatrix is more concentrated near the divertor.
Author: Steven William Lisgo Publisher: National Library of Canada = Bibliothèque nationale du Canada ISBN: 9780612846494 Category : Magnetohydrodynamics Languages : en Pages : 180
Author: Brian LaBombard Publisher: ISBN: Category : Languages : en Pages : 80
Book Description
A specialized arrangement of gas-puff capillaries and in-situ pressure gauges has been installed in Alcator C-Mod to allow gas conductances and flows around divertor structures to be measured with or without plasma present in the chamber. Results are presented from a series of dedicated experiments performed during the 1020725 run day (MP#313, "Instrumented Divertor Leakage Experiments"). Gas conductances and flows are compiled in this report with the aim of providing good benchmark points for numerical simulations of gas flow and "plasma plugging" physics in Alcator C-Mod. A strong plasma plugging effect is found at locations where the divertor structure is opened for diagnostics access (the so-called "open-port" locations), as evidenced by a factor of [approx.] 4 reduction in the local gas conductance with plasma present. The effect is most dramatic for locations in the upper chamber region where there is no neutral baffle structure; a factor of [approx.] 5 reduction in the local gas conductance is found there. Gas conductance through an open divertor flap is measured to be a factor of [approx.] 3 lower than that which has been commonly assumed using the area of the open flap. The conductance through the flap is found to be similar with or without plasma present, indicating that there is no "plasma plugging" effect occurring at this location. The gas flow rate through a flap that is adjacent to an "open-port" location is found to be a factor of 2 lower than at a location distant from open ports. The latter result suggests that significant toroidal variations in the pressures exist under the lower divertor modules.
Author: United States. Congress. House. Committee on Science. Subcommittee on Energy and Environment Publisher: ISBN: Category : Political Science Languages : en Pages : 682
Author: Publisher: ISBN: Category : Languages : en Pages : 4
Book Description
Experiments on Alcator C-Mod with toroidally and poloidally localized divertor nitrogen injection have been modeled using the three-dimensional edge transport code EMC3-EIRENE to elucidate the mechanisms driving measured toroidal asymmetries. In these experiments five toroidally distributed gas injectors in the private flux region were sequentially activated in separate discharges resulting in clear evidence of toroidal asymmetries in radiated power and nitrogen line emission as well as a ~50% toroidal modulation in electron pressure at the divertor target. The pressure modulation is qualitatively reproduced by the modelling, with the simulation yielding a toroidal asymmetry in the heat flow to the outer strike point. Finally, toroidal variation in impurity line emission is qualitatively matched in the scrape-off layer above the strike point, however kinetic corrections and cross-field drifts are likely required to quantitatively reproduce impurity behavior in the private flux region and electron temperatures and densities directly in front of the target.
Author: David R. Schultz Publisher: American Inst. of Physics ISBN: 9780735400900 Category : Science Languages : en Pages : 328
Book Description
The APS Topical Conference on Atomic Processes in Plasmas brings together researchers working in atomic physics and in plasma science, emphasizing the strong and synergistic overlap of these fields. The latest developments in atomic physics reported are recent advances in plasma science, such as in magnetic or inertial confinement fusion, Z-pinches, astrophysics, and technical plasma processing.
Author: Taekyun Chung
Author: Taekyun Chung![Interpretive Modeling of the Alcator C-Mod Divertor [microform] PDF](https://books.google.com/books/content/images/frontcover/ujubtgAACAAJ?fife=w80-h100)
Author: Steven William Lisgo
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Author: D. P. Stotler
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Author: Brian LaBombard
Author: United States. Congress. House. Committee on Science. Subcommittee on Energy and Environment
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Author: 
Author: David R. Schultz